Centre of Mass and Body Position in Sports
Understanding Centre of Mass (COM)
The centre of mass is the point where all of the body's mass appears to be concentrated. Think of it as your body's balancing point! In a standing position, your COM is typically located just in front of your second sacral vertebra (around your belly button).
NoteThe position of your COM isn't fixed - it changes as you move and adjust your body position.
How Body Position Affects COM
1. Vertical Changes
When you change your body position vertically, your COM shifts accordingly:
- Standing straight: COM is about waist height
- Crouching: COM lowers
- Jumping: COM rises
In high jump, athletes use the Fosbury Flop technique to clear the bar. By arching their back, they can actually get their COM to pass under the bar while their body passes over it - pretty neat, right?
2. Horizontal Changes
Shifting your body parts horizontally also moves your COM:
- Arms forward: COM moves forward
- Leaning back: COM moves backward
- Sideways lean: COM shifts laterally
Sports Applications
Gymnastics
- Balance beam routines require constant COM adjustments
- Extending arms helps maintain balance
- Tucking during somersaults speeds rotation by bringing COM closer to axis
Diving
- Changing body position affects rotation speed
- Tucked position: faster rotation
- Extended position: slower rotation
Athletes can control their rotation speed by adjusting how tightly they tuck their body - the tighter the tuck, the faster the rotation!
Track and Field
- Long jump: forward lean shifts COM ahead
- Shot put: side lean helps transfer momentum
- Sprint start: low COM position enables explosive forward movement
Practical Implications
Balance and Stability
- Lower COM = More stable position
- Wider base of support improves stability
- COM should stay within base of support
Many athletes forget that raising their arms above their head raises their COM, potentially decreasing stability in standing positions.
Performance Enhancement
- Understanding COM helps optimize technique
- Proper COM manipulation can:
- Increase jump height
- Improve balance
- Enhance rotation control
- Maximize power transfer
When learning new sports skills, focus on how your body position affects your balance and movement - this awareness will help you understand how COM changes impact performance.
